SyntaxError: missing ; before statement

SyntaxError: Expected ';' (Edge)
SyntaxError: missing ; before statement (Firefox)

SyntaxError.

There is a semicolon (;) missing somewhere. JavaScript statements must be terminated with semicolons. Some of them are affected by automatic semicolon insertion (ASI), but in this case you need to provide a semicolon, so that JavaScript can parse the source code correctly.

However, oftentimes, this error is only a consequence of another error, like not escaping strings properly, or using var wrongly. You might also have too many parenthesis somewhere. Carefully check the syntax when this error is thrown.

This error can occur easily when not escaping strings properly and the JavaScript engine is expecting the end of your string already. For example:

const foo = 'Tom's bar';
// SyntaxError: missing ; before statement

You can use double quotes, or escape the apostrophe:

const foo = "Tom's bar";
// OR
const foo = 'Tom\'s bar';

You cannot declare properties of an object or array with a let, const, or var declaration.

const obj = {};
const obj.foo = "hi"; // SyntaxError missing ; before statement

const array = [];
const array[0] = "there"; // SyntaxError missing ; before statement

Instead, omit the keyword:

const obj = {};
obj.foo = "hi";

const array = [];
array[0] = "there";

If you come from another programming language, it is also common to use keywords that don't mean the same or have no meaning at all in JavaScript:

def print(info) {
  console.log(info);
} // SyntaxError missing ; before statement

Instead, use function instead of def:

function print(info) {
  console.log(info);
}

• Automatic semicolon insertion (ASI)
• JavaScript statements